In next generation multimedia mobile communication systems, which have been actively studied in recent years, there is a demand for a system capable of processing and transmitting a variety of information (e.g., video and radio data) at a higher data rate in addition to the early-stage voice service.
Orthogonal frequency division multiplexing (OFDM) capable of having a high data rate has drawn attention in recent years. The OFDM is a multi-carrier modulation scheme for transmitting data by dividing a frequency band into a plurality of orthogonal subcarriers. Orthogonal frequency division multiple access (OFDMA) is a scheme for providing multi-user multiplexing by combining the OFDM with frequency division multiple access (FDMA), time division multiple access (TDMA), or code division multiple access (CDMA).
A wireless communication system includes a base station (BS) and at least one user equipment (UE). The UE may be fixed or mobile, and may be referred to as another terminology, such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), a wireless device, etc. The BS is generally a fixed station that communicates with the UE and may be referred to as another terminology, such as an evolved node-B (eNB), a base transceiver system (BTS), an access point, etc. Hereinafter, an uplink (UL) denotes a communication link from the UE to the BS, and a downlink (DL) denotes a communication link from the BS to the UE.
For effective system configuration, the wireless communication system has a cell structure. A cell is a region in which a wide area is divided into small areas for effective frequency use. In general, the BS is installed in a center of the cell to relay the UE, and the cell corresponds to a service area of one BS.
If the same subcarrier is used by neighbor cells of an OFDM/OFDMA system in a multi-cell environment, users may experience interference. This is referred to as inter-cell interference. In particular, the inter-cell interference is seriously problematic for a UE located near a cell boundary. When the UE is located near the cell boundary in DL transmission, the UE experiences strong interference from the neighbor cells. When the UE is located near the cell boundary in UL transmission, the UE produces strong interference to the neighbor cells, and has a low data rate due to a path loss in a serving cell.
A multi-cell cooperation scheme supporting inter-cell cooperation is proposed to reduce inter-cell interference and to satisfy high data rate and system performance. A new type of control signal is required when using the multi-cell cooperation scheme. In addition, inter-cell signal processing requires a large amount of control signals, and thus there is a need for an effective control mechanism.
A multi-cell cooperation scheme supporting inter-cell cooperation requires a new type of control signal and control mechanism.